1. Field of the Invention
The present invention relates to a transflective film and a liquid crystal display device using the same.
2. Description of the Related Art
Since the battery life of portable electronic apparatuses, such as a mobile phone and a portable game device, considerably affect the use thereof, the portable electronic apparatuses are provided with reflective liquid crystal display devices capable of reducing power consumption as display units. For example, the reflective liquid crystal display device comprises a reflector that totally reflects external light incident from the front side of the reflective liquid crystal display device or a reflector that reflects external light incident from the front side of the reflective liquid crystal display device and transmits backlight incident from the backside of the reflective liquid crystal display device. As such a reflector, a reflector, on which a plurality of fine concave portions or convex portions is formed, is widely known in order to maximize the reflectance of light (for example, see Patent Document 1).
[Patent Document 1]
Japanese Unexamined Patent Application Publication No. 2003-14912
In particular, a reflector, which reflects external light incident from the front side of the reflective liquid crystal display device and transmits backlight incident from the backside thereof, is referred to as a transflector. For example, as shown in FIG. 9, a transflective film 101, in which an opening 103 corresponding to each pixel 106 of a liquid crystal display panel is provided in a portion of a thin metallic film having a plurality of fine concave portions (dimples) 102, is used as the transflector. The transflective film 101 transmits light emitted from an illuminating device, such as a backlight, to the liquid crystal display panel through the opening 103 and reflects external light from a reflecting region 104 other than the opening 103 to travel the reflected light to the liquid crystal display panel. In this way, the liquid crystal display panel can be illuminated no matter whether external light or the illuminating device is used as a light source.
When external light incident through the liquid crystal display panel is reflected to the liquid crystal display panel again, the fine concave portions 102 formed on the surface of the transflective film 101 reflect the incident external light effectively in a wide range. As marked by the symbol Q1 in FIG. 9, when a predetermined number of concave portions 102, for example, sixteen concave portions 102 that are arranged in four rows of four concave portions is formed as one unit, the desired reflection characteristics are obtained.
However, in the above-mentioned conventional transflective film 101, since the desired reflection characteristic is obtained using sixteen concave portions 102 that are arranged in four rows of four concave portions as one unit, one or two columns or rows of concave portions 102 situated within an interval t1 in the width direction between the outer circumference 103a of the opening 103 and the edge 106a of the pixel 106 make only a small contribute to reflection. If regions that correspond to one or two columns or rows of concave portions 102 formed around the opening 103 do not contribute to reflection, the liquid crystal display panel is not effectively illuminated by external light, and it is impossible to improve the luminance of the liquid crystal display panel.